This invention generally relates to aluminum plate oil coolers. With more particularity, the invention relates to aluminum plate oil coolers having an internal and external center covering the entire surface of the plates forming the aluminum plate oil cooler. xe2x80x9cCenterxe2x80x9d refers to the individual finned surfaces in contact with the oil cooler plates. The centers can be positioned internally (oil side) or externally (water or coolant side) of the oil cooler.
Plate oil coolers are used to cool transmission or engine oil utilized in cars and trucks. The oil coolers are placed in the vehicle radiator inlet or outlet coolant tanks to provide a means for exchanging the heat from the oil to the coolant. Plate oil coolers are produced utilizing a variety of metals. Construction materials include cupre-nickel and stainless steel plates with steel fin or center surfaces braced between the plates. The fin surfaces turbulate or mix the oil and improve the surface area available for heat transfer from the oil to the coolant.
In an effort to reduce the costs associated with the production of automobiles as well as improve the mileage performance of automobiles, alternative materials such as aluminum have been considered for use in plate oil cooler designs. The aluminum oil coolers have advantages over conventional materials, such as a substantial weight savings due to the lower density of aluminum, as compared to the higher density stainless steel construction materials. Aluminum also has a higher thermal conductivity as compared to some of the common construction materials; thereby, allowing additional cost and weight savings by eliminating the need for one or more plates from a conventional design.
One drawback of utilizing aluminum as a construction material is the lower yield strength as compared to other construction materials such as stainless steel. Because of the high pressure, usually from 50 to 150 PSI, that an oil cooler must contain under typical operating conditions and the subsequent burst requirements of up to 500 psi, special design considerations must be utilized for aluminum plate coolers.
Accordingly, it is an object of the present invention to provide an aluminum plate oil cooler that has an increased burst strength and pressure cycle life. It is also an object of the present invention to provide an aluminum plate oil cooler that may be manufactured with an increased strength and resistance to leaks by a brazing operation.
There is provided, an aluminum plate oil cooler which cures those deficiencies outlined above and provides an oil cooler having excellent durability, increased strength and is easier to manufacture. The aluminum plate oil cooler of the present invention includes a plurality of pairs of plates that are secured along their perimeter to define an oil flow path. The plates include embossed regions that are formed to provide inlet and outlet ports for the oil. Top and bottom reinforcement plates are positioned at the top and bottom of the plurality of pairs of plates. An internal center is positioned between the plates to increase the heat transfer area and turbulate the oil within the oil cooler. An external center is positioned between each of the plurality of pairs to increase the thermal transfer area on the coolant side of the oil cooler. The external center is a corrugated aluminum sheet having fins formed on the sheet such that the flow of the coolant is perpendicular to the flow of the oil. The external center covers the entire surface of the plates and includes holes formed to correspond with the embossed regions on the plates. This design provides a uniform internal load on the plates to insure a quality bond between the internal center and plates during a brazing operation.